Bumper system with energy absorber

ABSTRACT

A bumper system includes a bumper beam having a face and ends, and an energy absorber mounted on the face. The energy absorber has a one-piece injection-molded non-foam piece with box sections and interconnecting straps, and a one-piece or multi-piece foam component securely insert-molded onto the injection-molded non-foam piece. Different foam molds can be used to form differently shaped front surfaces on the foam component. By this arrangement, different energy absorbing systems are provided for vehicles, such as to satisfy the need for different styling and shapes, while still using the same non-foam piece. By this arrangement, the energy absorber is a single unit that can be handled and attached to the bumper beam. At the same time, capital investment in molding dies and tooling is reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of commonly assigned, co-inventedapplication Ser. No. 11/313,325, FILED Dec. 21, 2005 entitled BUMPERSYSTEM WITH ENERGY ABSORBER, now U.S. Pat. No. 7,172,227, which is acontinuation of commonly assigned, co-invented application Ser. No.10/694,278 filed on Oct. 27, 2003, entitled BUMPER SYSTEM WITH ENERGYABSORBER, now U.S. Pat. No. 7,052,056, which is a divisional of commonlyassigned, co-invented application Ser. No. 10/163,586 filed on Jun. 6,2002, entitled BUMPER WITH INTEGRATED FOAM AND NON-FOAM COMPONENTS, nowU.S. Pat. No. 6,672,635.

BACKGROUND

The present invention relates to vehicle bumper systems having an energyabsorber on a bumper beam, and more particularly relates to a bumpersystem having an energy absorber on the beam that is adapted to providedifferent levels of energy absorption in selected areas but furtheradapted to take maximum advantage of mass production.

Vehicle bumper systems often include a bumper beam for strength and amounted energy absorber to help absorb energy and distribute stressacross the bumper beam during impact. However, each different modelvehicle requires a slightly different shape or different energyabsorption profile, such that each different model vehicle requires adifferent mold for the energy absorber. Each additional mold isexpensive, because they are relatively large and long. Further, it takestime and labor to change molds, and requires downtime of the moldingmachine.

Accordingly, a bumper system is desired that includes an energy absorbersolving the aforementioned problems and having the aforementionedadvantages.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, a bumper system has a face andends, and has an energy absorber mounted on the face. The energyabsorber has an injection-molded piece and a foam piece attached to theinjection-molded piece, with the injection-molded piece being one-piecewith box-shaped sections interconnected by strap sections, and with thefoam piece being one-piece and encapsulating the straps and engaging atleast a side of the box-shaped sections.

In another aspect of the present invention, a bumper system includes abumper beam having a face surface, and an energy absorber engaging theface surface, where the energy absorber has an elongated non-foaminjection-molded component with at least three longitudinally-spacedenlarged sections. An enlarged foam component is attached to theinjection-molded component, with the enlarged foam component havingfirst foam sections positioned between the enlarged sections and havingsecond foam sections on the enlarged sections.

In yet another aspect of the present invention, a method comprises stepsof molding a non-foam plastic component having box sections and strapsections connecting the box sections, and molding a foam component thatencapsulates at least three sides of the strap sections and that isbonded to at least part of the box sections, including forming a finalproduct that can be handled as a unit. The method further includesengaging the unitary member against a face of a bumper beam.

In still another aspect of the present invention, a method comprisessteps of providing molding dies for molding a non-foam plastic componenthaving box sections interconnected with strap sections, such that theplastic component is shaped for use in a bumper system for providing anenergy-absorbing impact strength, and also providing at least first andsecond molds for molding first and second foam components onto theplastic component, the first and second molds having respective cavitiesconfigured to form differently shaped front surfaces on the first andsecond foam components. The method includes molding the non-foam plasticcomponent using the molding dies, and using the selected one mold in amolding process to form an associated one of the foam components,including attaching the associated foam component to the one of thenon-foam plastic components to form a first energy absorber bumperproduct that can be handled as a unit. The method further includesengaging the unitary bumper product against a face of a bumper beam.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a fragmentary perspective view of a bumper system including abumper beam and a face-mounted energy absorber;

FIGS. 2-3 are cross sections taken along the lines II-II and III-III inFIG. 1;

FIG. 4 is a front perspective view of a second bumper system including abumper beam and a modified face-mounted energy absorber;

FIG. 5 is a rear perspective view of the energy absorber shown in FIG.4;

FIGS. 6-7 are top and front views of FIG. 4;

FIGS. 8-10 are front perspective, front, and top views of a third bumpersystem;

FIG. 11 is a rear perspective view of the energy absorber shown in FIG.8;

FIG. 12 is a front perspective view of an injection-molded non-foam“solid” plastic component of the energy absorber shown in FIG. 8; and

FIG. 13 is a top view of a fourth bumper system, utilizing theinjection-molded non-foam plastic component shown in FIG. 12 but havingfirst and second enlarged foam components molded thereon, the firstbeing shown in solid lines, the second in phantom lines;

FIGS. 14-15 and FIGS. 16-17 are cross sections taken along the linesXIV-XIV and XV-XV, respectively. FIGS. 14-15 are cross sections of theembodiment shown in solid lines, and FIGS. 16-17 are cross sections ofthe embodiment shown in phantom lines; and

FIG. 18 is an exploded view of a modified version of the non-foamcomponent shown in FIG. 12.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A bumper system 8 (FIG. 1) includes a bumper beam 16 having a face andends, and an energy absorber 10 mounted on the face. The energy absorber10 has a center-located foam piece 11 engaging the face and aninjection-molded end piece 12 securely attached to each end of the foampiece and also engaging the face. By this arrangement, the energyabsorber 10 is a single unit that can be handled and attached to thebumper beam 16. Also, the energy absorber 10 can include different endpieces while still using the same foam piece, or alternatively, theenergy absorber can include different center pieces while using the sameinjection-molded non-foam end pieces. Thus, the present inventiveconcepts provide the advantages of smaller molding dies for molding theinjection-molded non-foam components. This is important because moldingdies for injection-molded components are considerably more expensivethan molding dies for foam components. At the same time, the presentmethods and apparatus provide the advantages of a single large energyabsorber component that can be handled.

More specifically, the illustrated energy absorber 10 of FIG. 1 isadapted to advantageously use a common center piece 11 made of foam, andany one of a variety of different injection-molded end pieces attachedto the foam. The illustrated end piece 12 includes loops or attachmentflanges 13 and is insert-molded onto an end of the foam piece 11 whenforming the foam piece 11. The end piece 12 includes a front surface 14angled to match the corner of its particular vehicle, and a notched backsurface 15 shaped to mateably receive an end of the bumper beam 16 thatit rides on. It is contemplated that different attachment means can beused to attach pieces 11 and 12 together, including adhesive, mechanicalattachment, different tabs for insert-molding into the foam, andbarb-like tabs that can be poked into the foam, etc. Since the samecenter piece is used for a number of different models, the overall costof molding dies is greatly reduced. Restated, the cost of several smallinjection-molding dies for molding a variety of different end pieces,added to the cost of one large die for the foam center piece, is muchlower than the cost of making a multitude of different hugeinjection-molding dies for each energy absorber.

The same principle applies to a bumper system that uses the same endpieces but different foam molding dies. Restated, the cost of a singleset of small injection-molding dies for molding the end pieces, added tothe cost of several large dies for making different foam center pieces,is much lower than the cost of making a multitude of different hugeinjection-molding dies. This concept is discussed in greater detailbelow. (See FIGS. 13-17, and see discussion below.)

A second energy absorber 10 a (FIGS. 4-7) is mounted to a face of abumper beam 16 and includes a center-located injection-molded non-foamplastic center piece 20, foam pieces 11 attached to each end of thecenter piece 20, and injection-molded non-foam end pieces 12 attached toouter ends of each of the foam pieces 11. The pieces 11, 12, and 20 areeach molded for optimal localized energy absorption (i.e. for an optimalforce versus deflection curve, as well as for total energy absorptionbased on localized/area-specific impacts and based on particular typesof impacts). For example, the injection-molded pieces 12 and 20 includea plurality of interconnected webs forming a honeycomb structure capableof substantial energy absorption prior to deformation of the bumper beamitself.

A modified bumper system (FIGS. 8-10) includes a roll-formed B-shapedbumper beam 16 and a modified energy absorber 30 b abutted against itsface surface. The energy absorber 30 b includes an injection-moldedpiece 31 b (FIG. 12), and one or more foam pieces 11 b (FIGS. 8-11)molded onto the injection-molded piece 31 b. The injection-molded piece31 b (FIG. 12) is molded of a non-foam “solid” polymer and includesmolded end sections 32 b (similar to end pieces 12), and molded centerand intermediate sections 33 b and 34 b, all interconnected bylongitudinal straps 35 b. The end sections 32 b (when seen in plan view)each include a triangular outer portion 36 b and a triangular innerportion 37 b forming a rearwardly-swept angled front surface 38 b and astepped back surface 39 b with a pocket 40 b shaped to receive the endof the beam 16. The outer portion 36 b includes four parallel walls 41 bthat extend parallel a length of the beam 16, and that combine withangled walls 42 b and 43 b to define a honeycomb-like structure in theform of three forwardly open pockets 44 b. The inner portion 37 b hasfour parallel walls 45 b that combine with angled walls 46 b and 47 b todefine a rigid structure on the face of the end of the bumper beam 16.The honeycomb-like structure of the outer portion 36 b and the innerportion 37 b combine to provide optimal energy absorption at ends of thebumper beam 16 for optimal corner impact resistance and crushcharacteristics. The walls 41 b and 45 b are generally parallel andaligned with each other and extend in a horizontal plane (when in acar-mounted position), such that good corner impact strength isprovided. It is noted that the inner and outer portions 36 b and 37 bare configured to allow a simple molding die, without the need formaking undercuts, blind surfaces, and without the need for complex diepulls and slides.

The center and intermediate sections 33 b and 34 b (FIG. 12) eachcomprise rearwardly-open box-shaped sections formed by side walls 50 b,a top wall 51 b, a bottom wall 52 b and a front wall 53 b. An opening 54b is formed in each of the front walls 53 b, and a centered tubular“crush tower” of material 55 b extends rearwardly from the marginalmaterial forming the opening 54 b to a rear of the energy absorber. Thebox-like shape of walls 50 b/51 b/52 b/53 b along with the crush tower55 b adds considerably to the impact strength of the energy absorber 30b and adds control over the crush sequence and characteristics of impactand bumper system crush stroke versus energy absorption. If the crushtower 55 b ends short of the bumper beam 16, then the crush sequence hasa stepped function, where the initial crush strength is a little lower,and when the energy absorber 30 b crushes to the point where the crushtower 55 b hits the bumper beam 16, the impact strength suddenlyincreases for additional crush stroke distances. Also, the top andbottom walls 51 b and 52 b are wavy or undulated to provide increasedimpact strength.

The straps 35 b (FIG. 12) extend between and interconnect each of thesections 32 b, 33 b, and 34 b. Their cross sections define arearwardly-facing U-shape, and are formed by front wall 57 b, and topand bottom walls 58 b and 59 b. The straps 35 b permit flexing movement,until the foam sections 11 b are molded onto the pieces 31 b, at whichtime the energy absorber 30 b becomes stiff enough to easily handle andassemble onto the bumper beam 16.

It is noted that the entire illustrated energy absorber 30 b isconfigured so that it can be molded by a relatively simple molding die,where the die halves do not include draws, slides, and other movingcomplex components for making blind and/or hidden surfaces. This greatlysimplifies and improves tooling, and reduces costs and capitalinvestment of making the die and keeping the die maintained andoperational.

The energy absorber 30 b can be attached temporarily to the tubular beam16 by various means. For example, the illustrated absorber 30 b includesrearwardly-extending resilient attachment flanges or “fingers” 70 b ontop and bottom walls of the energy absorber 30 b. The fingers 70 binclude a protrusion 71 b adapted to engage a mating aperture in thebeam 16 for temporarily securing the energy absorber 30 b to the beam16. The assembly 30 b/16 can then be handled as a unit to facilitatetransporting, placing, and then securing the assembly 30 b/16 on thevehicle.

FIG. 13 is a top view of a fourth bumper system 8 b′, utilizing amodified energy absorber 30 b′. The energy absorber 30 b′ includes thesame injection-molded non-foam plastic component 31 b shown in FIG. 12,but also includes an enlarged one-piece foam component 11 b′ (shown insolid lines) or one-piece foam component 11 b″ (shown in phantom lines)molded thereon. It is contemplated that the foam piece will be madeunique to each different vehicle model (i.e. each different fasciastyle), but the injection-molded part will be the same for each vehiclemodel (i.e. despite the different fascia style, the same non-foam partcan be used.) Advantageously, the foam component (11 b′ and/or 11 b″)can have a different top surface shape or bottom surface shape. Forexample, compare the energy absorber 30 b′ illustrated by solid lines inFIG. 13, with the energy absorber 30 b″ illustrated by phantom lines inFIG. 13. Also, compare the energy absorber 30 b′ in FIGS. 13-15, withthe energy absorber 30 b″ in FIGS. 13, 16-17.

Energy absorber 30 b′ (or 30 b″) can be further modified as shown inFIG. 18, by making the end piece telescopingly adjustable on the maincenter piece. In the modification, the end piece 32 b″ is separated fromthe interconnecting section 35 b″ of center piece 31 b″, and the endpiece 32 b″ is given an integrally-formed free-ended interconnecting leg80 bshaped to telescope into an open end 81 b of the interconnectingsection 35 b″. The interconnecting section 35 b″ includes inward flanges82 b shaped to capture a cross-sectional shape of the interconnectingleg 80 b, and further the interconnecting leg 80 b includes protrusions83 b shaped to detentingly engage the apertures 84 b in theinterconnecting leg 80 b.

By this arrangement, the end piece 32 b″ can be adjustinglysnap-lockingly engaged with the interconnecting section 25 b to apredetermined length. Thus, the same non-foam injection-molded energyabsorber assembly (i.e. center piece 31 b″ and end pieces 32 b″) can beassembled to a desired length for use on a particular model vehiclehaving a car-width dimension greater than that shown in FIG. 13. It isnoted that the telescoping feature (i.e. leg 80 b) can be locatedanywhere along a length of the energy absorber, and not just at its end.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent invention, and further it is to be understood that such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise.

1. A method comprising steps of: molding a plurality of non-foam plasticcomponents each having box sections and strap sections connecting thebox sections; molding a foam component that encapsulates at least threesides of one of the strap sections and that is bonded to at least partof the box sections, including forming a final product that can behandled as a unit; and engaging the unitary member against a face of abumper beam.
 2. The method defined in claim 1, wherein: the non-foamplastic component is one-piece.
 3. The method defined in claim 1,wherein: the foam component is one-piece.
 4. A method comprising stepsof: providing molding dies for molding a non-foam plastic componenthaving box sections interconnected with strap sections, such that theplastic component is shaped for use in a bumper system for providingenergy-absorbing impact strength; providing at least first and secondmolds for molding first and second foam components onto the plasticcomponent, the first and second molds having respective cavitiesconfigured to form differently shaped front surfaces on the first andsecond foam components; molding a plurality of the non-foam plasticcomponents using the molding dies; selecting one of the first and secondmolds; using the selected one mold in a molding process to form anassociated one of the foam components, including attaching theassociated foam component to the one of the non-foam plastic componentsto form a first energy absorber bumper product that can be handled as aunit; and engaging the unitary bumper product against a face of a bumperbeam.
 5. The method defined in claim 4, further including: selecting theother of the first and second molds, using the selected other mold toform an associated second one of the foam components, includingattaching the second associated foam component to another one of thenon-foam plastic components to form a second energy absorber bumperproduct that can be handled as a unit, the second energy absorber bumperproduct being different than the first energy absorber bumper product.